An ultrasonic receiver can be used to determine the location of items that contain ultrasonic emitters, such as a mobile device present within a retail, factory, or warehouse environment, for example. The ultrasonic emitters can transmit ultrasonic energy in a short burst which can be received by an ultrasonic transducer (microphone) in the ultrasonic receiver, thereby establishing the presence of the device within the environment. The ultrasonic emitters can also transmit information to the receiver in an ultrasonic signal for data communication.
Further, the use of several ultrasonic microphones distributed within the environment can also be used to provide a specific location of a particular mobile device using techniques known in the art such as triangulation, trilateration, and the like. However, unlike radio frequency locationing systems, ultrasonic locationing systems suffer from particular problems related to the character of ultrasonic sound waves and their environment of use. Firstly, ultrasonic signals are easily subject to noise. Secondly, ultrasonic waves are typically subject to acoustic reverberation due to multipath reflections. Therefore, signals sent by emitters can be interfered with by reverberations. This problem is compounded when there are multiple emitters that are emitting a signal.
Accordingly, there is a need for an improved technique to resolve the above issues within an ultrasonic locationing system.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.